Greetings! I have owned a 1997 model coach equipped with a Cummins purely mechanical C 8.3 engine and would appreciate knowing how often the air filter should be changed. I installed the current air filter two years ago and the filter restriction gauge has only moved slightly to "8". Wondering if it should be replaced after a certain number of months or mileage interval irregardless of the filter-minder gauge reading? The filter has about 15,000 miles on it. THANK YOU very much, Jeff...

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Just changed mine after 4 years. Filter minder was edging up towards 20.

Old filter was clean as a whistle on the clean air side. Paper element appeared as new.

Inside (dirty side) the filter was dirty, but not excessively so.

There are 2 schools of thought that I am aware of.

One is the recent Spartan recommendation for an annual change due to some failures of the paper element in a fire engine application which resulted in the paper element entering the turbocharger and causing a failure.

The other is that a used filter actually filters better than a new filter and that you should not prematurely change the filter. On our coach there is a written statement to not "over service" and your coach likely has the same statement from Spartan.

Also, Dave, how long have you owned your coach? Curious if the c 8.3 has had any issues other than routine maintenance? I bought my coach because of the 8.3 and its reputation for extreme dependability...???

Factory says...2 years from date of filter manufacture or when indicator says so.
Our instructor said "if you lose a filter it will end up in the turbocharger if you lose a turbocharger........... Makes a $80.00 filter seem pretty inexpensive. There are plenty of filters with many many miles (and years) on them. Decisions,decisions

Also, Dave, how long have you owned your coach? Curious if the c 8.3 has had any issues other than routine maintenance? I bought my coach because of the 8.3 and its reputation for extreme dependability...???

I call it my "trusty" C8.3. No issues in four years and approaching 30K miles.

I do use Optilube Summer Blend to increase fuel lubricity and reduce the wear on the lift pump.

Also use Valvtect Microbiocide and park it with a full tank to prevent any growth in the tank (learned that from the diesel boaters here in S. Florida).

I change the oil annually, replace both the fuel filters, the oil filter and the water filter (number of units depends upon SCA readings at the time of service).

Speedco oil analysis indicates that the engine is broken in and wear metals are minimal.

No smoke out of the tailpipe, starts instantly and I do not place my foot on the throttle when starting.

I also have the mechanical 8.3 and although i have had for only two years i am very happy so far. Good fuel economy, ample power, starts really good, and I use more oil checking it than burning it!!! My Moho weighs a shade over 22,000lbs with full liquids.

I purchased a 97 Imperial with the 8.3l 325hp engine over two years ago. I love it. Starts right up, no smoke, had the oil tested twice with excellent reports. Only problem is iis slightly underpowered when pulling my 29,000 lb coach with a 4500 lb toad up a 6% grade. You made a good choice.

Kben, it did until I made a slight adjustment to the injector pump. My coach has the 325hp engine option with the Banks Turbo Stinger kit installed. I have a turbo gauge and a pyrometer that I monitor. I now have pretty decent pick up in 1st and 2nd with no more hesitation in the mid range. Looking forward to taking it on a trip in a couple of weeks.
Steve